GCSE C4.1

Predicting chemical reactions

Why are group 1 metals called alkali metals?

They form an alkaline solution when they react with water

Why do alkali metals have similar chemical properties?

They have one electron on their outer shell

Properties of alkali metals?

• soft (can easily be cut with a knife)

• low density

• low melting point

• very reactive (only needs to lose 1 electron to become stable)

Trends of alkali metals?

• melting point decreases as you go down the group due to decreasing attractive forces between outer shell electrons and positive ions

• softer as you move down

• reactivity increases

Why does reactivity of alkali metals increase as you go down the group?

• the outer shell electrons get further away from nucleus so there are weaker forces of attraction between them

• less energy is needed to overcome the forces of attractions so outer electron is lost more easily

Why are alkali metals stored in oil?

They react readily with oxygen and water vapour in the air

What is produced when an alkali metal reacts with water?

Metal hydroxide + Hydrogen

Chemical equation for the reaction between sodium and water?

2Na (s) + 2H20 (l) --> 2NaOH (aq) +H2 (g)

What is formed when alkali metals react with oxygen?

Metal oxide

Reaction between Lithium and Oxygen

4Li + O2 --> 2Li2O

What is formed when alkali metals react with Chlorine?

Metal chloride

Reaction between Lithium and Chlorine?

2Li + Cl2 --> 2LiCl

What are group 0?

Noble gases

Properties of noble gases?

• inert

• low density

• low boiling/melting point

Meaning of inert? Why are noble gases inert?

unreactive
they have a full outer shell of electrons

Trends of noble gases

Boiling points increase as you go down due to an increase in atomic mass so more intermolecular forces that need more energy to break

Group 7 elements

Halogens

Properties of halogens

poisonous

non-metals

diatomic

reactive

increasing melting point

Why do the melting points of halogens increase as you go down the group?

increasing intermolecular forces so more energy needed to break them

Fluorine at room temp

yellow gas

Chlorine at room temp

pale green gas

Bromine at room temp

red-brown liquid orange in solution

Iodine at room temp

purple-black solid dark brown in solution

What are the halogens states on room temp?

fluorine and chlorine - gas

bromine - liquid

iodine - solid

Why do halogens have different states?

They have different melting and boiling points

Why does reactivity of halogens decrease as you go down?

the forces of attraction between the nucleus and outer shell decreases so harder for atoms to gain an electron

Properties of transition metals

• hard and strong

• lustrous

• good conductors of heat and electricity

• highly dense metals

• very high melting points

What do transition metals form?

colourful compounds

Which elements aren't transition metals and why?

Scandium and Zinc - they don't form colourful compounds

Transition metals can be used as ..

catalysts like in the haber process with iron